Codeigniter：使用load_class [英] Codeigniter: Use of load_class

问题描述

我正在编写自己的记录类，以将数据保存在数据库中。当我看看CI如何做我注意到有一个 log_message（）函数处理日志记录。有一个 load_class 函数我不能分配到CI用户指南中的任何内容。

1

希望有一些CI家伙如何回答： - ）

解决方案

简短答案：
您可以编写自己的日志类来覆盖默认的CI类：

  <？php 
 //这个文件是/application/libraries/MY_Log.php 
类MY_Log扩展CI_Log {
 public function write_log（$ level ='error'，$ msg，$ php_error = FALSE）
 {
 //将自己的日志功能放在这里。 
 //如果你希望它仍然像往常一样记录到一个文件，使用：
 parent :: write_log（$ level，$ msg，$ php_error）; 
} 
} 
  

长答案 / p>

load_class（）函数基本上是一个单例装载器。如果类已经加载，则返回上一个实例;否则，加载它并创建单例。这在CI的框架中是非常重要的。你必须知道，每次你调用，说，一个数据库函数，它是应用于同一个对象，而不是实例化一个新的（这将是非常混乱）。默认情况下，所有CI库都以此方式运行。

重要提示：它们在2.0版本中更改了此函数的显着性。以前，它只能从 / libraries 文件夹加载，但现在，它将从 / core 加载，

下面是加载过程，比如，Log类（从你的例子）：

  $ _ log =& load_class（'Log'）; 
 $ _log-> write_log（$ level，$ message，$ php_error）; 
  

这会依次执行以下检查：

1. 如果Log类已经存在，就完成了。


2. 如果没有，请先检查 / system / libraries 文件夹中的Log.php文件


3. 如果对于步骤＃2没有文件存在，现在为MY_Log.php文件（或任何您的子类前缀）检查 / application / libraries


4. 如果加载了默认的CI类（来自 / system 文件夹），但您必须 c / c $


5. 返回类的新实例（YOURS，如果存在）;否则返回类的新实例，它是CI_ *类）

我实际上从来不需要使用 load_class code>函数，因为它允许相当无缝地扩展。

因此，要覆盖一个类，首先找到原来的位置（通常 / system / libraries 或 / system / core ）。将您的扩展文件放在相应的 / application 文件夹中（这很重要！如果它在 / system / core 扩展必须在 / application / core 下）。使用 MY _ （或您在配置中设置的任何内容）为文件名和类名添加前缀，并将它扩展 CI _ 基类。

I am writing my own logging class to save data in a DB. As I looked how CI is doing I noticed there is a log_message() function which handles the logging. There is a load_class function I can't assign to anything in the CI user guide.

1 Why do they put this into an extra function?

2 What/where loads this function files from?

Hope there are some CI guys how can answer :-)

解决方案

Short answer: You can write your own log class to override the default CI class:

<?php
// this file is /application/libraries/MY_Log.php
class MY_Log extends CI_Log {
    public function write_log($level = 'error', $msg, $php_error = FALSE)
    {
        // Put your own logging function in here.
        // If you want it to still log to a file as usual, use this:
        parent::write_log($level, $msg, $php_error);
    }
}

Long answer:

The load_class() function is basically a singleton loader. If the class has already been loaded, return a previous instance; otherwise, load it and create the singleton. It is very important in a framework like CI. You have to know that every time you call, say, a database function, it is applying it to the same object, not instantiating a new one (that would get really messy). All CI libraries function this way by default.

An important note: they changed how this functions significantly in version 2.0. Previously, it would only load from the /libraries folder, but now, it will load from /core or wherever you specify when calling the function.

Here's the process for loading, say, the Log class (from your example):

$_log =& load_class('Log');
$_log->write_log($level, $message, $php_error);

This runs the following checks, in sequence:

1. If the Log class already exists, we're done. Return the singleton.
2. If not, first check the /system/libraries folder for a "Log.php" file
3. If no file existed for step #2, now check /application/libraries for a "MY_Log.php" file (or whatever your subclass prefix is set to in your configuration)
4. If it loaded the default CI class (from the /system folder), but you DO have an extended class under /application, load that class too.
5. Return a new instance of the class (YOURS if it exists; otherwise, it's the CI_* class)

I've actually never needed to use the load_class() function, as it allows extension fairly seamlessly. However, it's good to know how it works.

So, to override a class, first find where the original resides (usually /system/libraries or /system/core). Put your extending file in the corresponding /application folder (this is important! If it's under /system/core, the extension MUST be under /application/core). Prefix both the filename and the class name with MY_ (or whatever you set in your configuration), and have it extend the CI_ base class.

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